It's simply a different citation style; check the page headers in your translation, and you will see "i 47" and such. So, ignore the M, and look for "i 35" or "iii 16", to use your examples.

"And how is it, bhikkhus, that by protecting oneself one protects others? By the pursuit, development, and cultivation of the four establishments of mindfulness. It is in such a way that by protecting oneself one protects others.

"And how is it, bhikkhus, that by protecting others one protects oneself? By patience, harmlessness, goodwill, and sympathy. It is in such a way that by protecting others one protects oneself.- Sedaka Sutta [SN 47.19]

Thank you Dmytro! That is a very complicated system that I finaly understand (I think); and outdated.

He turns his mind away from those phenomena, and having done so, inclines his mind to the property of deathlessness: 'This is peace, this is exquisite — the resolution of all fabrications; the relinquishment of all acquisitions; the ending of craving; dispassion; cessation; Unbinding.' (Jhana Sutta - Thanissaro Bhikkhu translation)